US4103276A - Resistor core cable - Google Patents

Resistor core cable Download PDF

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Publication number
US4103276A
US4103276A US05/705,363 US70536376A US4103276A US 4103276 A US4103276 A US 4103276A US 70536376 A US70536376 A US 70536376A US 4103276 A US4103276 A US 4103276A
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United States
Prior art keywords
cable
resistors
loop
length
inches
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/705,363
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English (en)
Inventor
James L. Kennon
Robert E. Sandorf
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Nordson Corp
Original Assignee
Nordson Corp
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Filing date
Publication date
Application filed by Nordson Corp filed Critical Nordson Corp
Priority to US05/705,363 priority Critical patent/US4103276A/en
Priority to CA280,795A priority patent/CA1088167A/fr
Priority to DE19772731356 priority patent/DE2731356A1/de
Priority to FR7721819A priority patent/FR2358734A1/fr
Priority to GB29488/77A priority patent/GB1583056A/en
Priority to JP52083630A priority patent/JPS6047683B2/ja
Priority to IT50272/77A priority patent/IT1079309B/it
Application granted granted Critical
Publication of US4103276A publication Critical patent/US4103276A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/0054—Cables with incorporated electric resistances

Definitions

  • This invention relates generally to high voltage electrical cables used to connect an electrostatic spray coating gun to a high voltage power supply, and more particularly relates to a high voltage cable wherein the conductive path of the cable includes distributed solid resistors.
  • High voltage electrical cables comprising distributed solid resistors throughout the cable length have been known in both the automotive industry for spark plug cables, and in the electrostatic spray coating industry for high voltage electrical power cables. In the electrostatic spray coating industry such cables have been used for several years. For a discussion of the benefits of such cables to the Electrostatic Spray Coating Industry, reference can be made to U.S. Pat. No. 3,348,186 issued to S. R. Rosen and assigned to the assignee of the present invention. However, prior art cables such as this did exhibit drawbacks for which it is an object of this invention to overcome.
  • the carbon composition resistors were brittle, and therefore if the cable were stepped on or run over with a truck or the like they would fracture and hence could cause failure of the cable. Further, because there were so many resistors in such close proximity to each other, the cable itself was very stiff and bulky.
  • the dielectric sheathing might be considered flexible by some standards, but stiff by others. That is, it will bend, but if it has any appreciable radial thickness it would no be considered limp.
  • the present invention is an improved high voltage cable having distributed resistance along the electrical path of the cable.
  • the cable consists of a core, continuously sheathed along its length by a resilient dielectric insulation.
  • the electrical path is through the core of the cable.
  • the core comprises a series of individual, elongated, rigid, but non-brittle resistors connected end to end by means of flexible conductive links.
  • the resistors are made from fiberglass rod having a resistive ink applied to the surface of the rod, and having pin-like electrical connecting posts extending from the ends of the rod.
  • the flexible conductive link betweeen resistors should be longer than the length of cable in a loop which has the minimum radius allowable for a similar cable assembly without the solid resistors.
  • a length can be defined as the "minimum allowable loop.”
  • the conductive links should be longer than a complete cable loop which could result in a one inch radius bend when the cable is pulled from its ends.
  • the dielectric sheathing materials in use today are made of materials such as polyethylene which exhibit some flexural elasticity. That is, upon being flexed from some preferred configuration the material will store energy just as any deformed spring will. The cable will take on a shape which minimizes the amount of energy stored. Stated in another way, when the cable is flexed forces will arise in the cable which would tend to cause the cable to return to its preferred configuration. Similarly, when a loop in a cable is pulled, the loop will take a shape which tends to minimize stored energy. If the cable is of uniform structure along its length, the loop will form into a smooth curve; the forces arising in the loop and the energy stored in the loop will be the same no matter which section of the cable contains the loop.
  • a flexurally elastic cable is not of uniform structure along its length, then the forces arising from a loop and the energy stored by a loop will depend on which section of the cable contains the loop. If the cable contains a section which has a higher modulus of flexural elasticity than an adjacent section, then the forces arising in the loop and the stored energy in the loop will be lower if the section having the higher modulus of elasticity is not in the loop.
  • a non-brittle rigid resistor effectively produces a section of a cable having a higher modulus of flexural elasticity than adjacent sections. A situation where the resistor is right at the middle of the loop is unstable in a loop formed in an infinitely long cable with no frictional forces acting.
  • the loop would always "travel" to a point which minimized stored energy (e.g., in a cable having multiple identical solid resistors, the loop would "travel" to a point midway between two successive resistors).
  • the instability of a resistor being located at the middle of a loop only exists for a given sized loop when the resistor is greater than some minimum length.
  • This minimum length for instability to occur can be selected as a function of several different criteria, for example: loop size; some minimum radius bend in the cable at the end of the resistor; or the force exerted at the ends of the cable.
  • This minimum length is influenced by forces arising in the cable which resist the ability of the loop to "travel" and hence resist the ability of the loop to form in an orientation which reduces stored energy to the minimum possible value.
  • Some of these forces are frictional in nature. They can arise from several sources: friction due to contact of the exterior of the cable with the surface on which the cable is lying; friction due to the contact of one part of the exterior of the cable to another part of the exterior of the cable where the loop crosses itself; frictional forces due to one layer of sheathing sliding over another layer when the cable is flexed; frictional type forces on the molecular lvel which resist flexing.
  • the resistors are made long enough to result in forces which will cause a tightly pulled loop to orient itself with the resistor necessarily out of the midpoint or small radius part of the loop under normal use.
  • normal use it is meant that the cable is resting, possibly coiled, on an industrial type floor, without any outside forces (other than its own weight) increasing the fractional forces. If it is desired to cause the rigid section of the cable to necessarily be out of the small radius part of a larger loop (or a loop less tightly pulled) then the length of the resistors needed would be greater.
  • FIG. 1 shows a partial cross sectional view of a preferred embodiment of a solid resistor core cable.
  • FIG. 2 shows a prior art resistor core cable with a resistor in a small radius portion of a pulled loop wherein a partial cross sectional view of the cable is shown around the resistor.
  • FIG. 3 shows an embodiment of the cable of the present invention with a pulled loop and showing a partial cross sectional view of the cable around the resistor.
  • the cable consists of a central core comprising a series of elongated resistors 1 connected to each other by means of flexible conductive links 2.
  • the resistors 1 comprise a fiberglass rod with resistive ink on the surface of the rod.
  • the resistors 1 are elongated cylinders having electrically conducting pins 4 at each end typical of the connectors on any common resistor. Successive resistors 1 are electrically joined together by a conductive link 2.
  • Vinyl, heavily loaded with carbon black, has been found to be a suitable material for use in forming the low resistance connecting links 2. This material is extremely flexible, is not subject to taking a set when flexed and has a low modulus of flexural elasticity.
  • the conductive link 2 is circular in cross secton in a plane passing through the link 2 perpendicular to the plane of FIG. 1 and has a hollow center slightly smaller in diameter than the diameter of the connecting pins 4 on the resistors 1.
  • the connecting pins 4 on the resistors 1 are inserted into the open hollow ends of the links 2 to make electrical contact with the link 2.
  • the outside diameter of the link 2 is substantially identical to that of the resistor 1.
  • a fiber braid 6 is woven around the central conductive core to provide longitudinal stability during the manufacturing process. Dacron can be used to make the fiber braid 6.
  • a ribbon 7 is spirally wrapped around the fiber braid 6 with a 50% overlap for the entire length of the cable.
  • the ribbon wrap helps to maintain a uniform outside diameter around the fiber braid 6.
  • the ribbon 7 can be of a material known by the DuPont tradename Mylar.
  • a high molecular weight low density polyethylene sheathing 8 is extruded continuously around the ribbon wrap 7 to provide an electrical dielectric insulation of 0.1 inch wall thickness around the core, fiber braid 6 and ribbon wrap 7.
  • Polyethylene is used because it provides good electrical high voltage insulation, is moderately flexible, and will not permanently deform when flexed in normal use.
  • the polyethylene is flexurally elastic.
  • a copper-weld braid 9 is woven around the polyethylene 8 for the length of the cable and is electrically connected to ground potential in use with an electrostatic spray coating system.
  • the entire assembly is then encased in a polyurethane jacket 10.
  • the jacket provides abrasion resistance for the complete assembly.
  • the diameter of the resistors 1 and conductive links 2 is 0.094 inches.
  • the polyethylene sheathing 8 has a radial thickness of 0.1 inches. With these dimensions it has been found that the minimum length of resistor which will necessarily become unstable at the center of the loop and travel out of a pulled loop in normal use is 0.7 inches. If a greater thickness of polyethylene sheath 8 were used, a greater length resistor 1 would be required to have the loop necessarily form in section not having the resistor at the midpoint of the loop when the loop is pulled. Conversely, if the thickness of polyethylene were reduced, then the resistor could be made shorter and still be incapable of remaining at the midpoint of a pulled loop.
  • the diameter of the resistors and conductive links is more or less controlled by the commercial acceptability of the cable for its intended use.
  • the radial dimensions of the components can range between one-half to twice the value used in the preferred embodiment. This limitation results at the smaller diameter from the availability of resistors having the proper resistance value in a given diameter size.
  • the upper limit of the diameter of these components is governed by the desirability to have a cable as small and flexible as possible. In a cable having dimensions in this range and made from the materials mentioned, the conductive links should be at least greater than 3 inches.
  • cables have been successfully constructed and tested having the following characteristics:
  • a 25-foot cable having 10 resistors 13/8 inches long with resistance value of 20 megohms each, connected by means of conductive links 30 inches long, and having other dimensions as in the preferred embodiment;
  • a 37-foot cable having 10 resistors 13/8 inches long of 20 megohms each, with the resistors being connected by conductive links which are 451/2 inches long and having other dimensions as in the preferred embodiment;
  • a 50-foot cable having 10 resistors 13/8 inches long with resistance of 20 megohms each, being connected by means of conductive links 60 inches long and having other dimensions as in the preferred embodiment.
  • the length of the resistor itself was chosen to be substantially longer than the minimum length required as described above. This added length provides a safety margin as far as the resistors remaining in a pulled loop, allows a greater range of resistance values for the individual resistors, if necessary, and results in a more flexible cable with improved structural integrity.
  • FIG. 2 shows a prior art cable having a pulled loop formed in it, with a resistor 12 which is 0.25 inches long and located initially at the center of the loop. Such a situation is typical of the loops encountered in actual use, wherein a resistor can randomly be in any portion of the loop. If the ends of the cable of FIG. 2 are pulled, the length of the resistor is not long enough to cause the loop to form in any preferred location.
  • the solid resistor 12 will cause deforming stresses in the sheath 8: the sheath 8 is bent over both ends of the resistor 12; and the sheath 8 is stretched at its outer circumferential portion around the resistor 12. Further, if the resistor were a carbon composition resistor, the stresses would result in fracture of the resistor.
  • FIG. 3 shows a cable identical to the preferred embodiment, with a pulled loop in it.
  • the length of the resistor is long enough to cause the loop to form in a portion of the cable such that the resistor is not at the midpoint of the loop when the loop is pulled.

Landscapes

  • Insulated Conductors (AREA)
  • Electrostatic Spraying Apparatus (AREA)
US05/705,363 1976-07-14 1976-07-14 Resistor core cable Expired - Lifetime US4103276A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US05/705,363 US4103276A (en) 1976-07-14 1976-07-14 Resistor core cable
CA280,795A CA1088167A (fr) 1976-07-14 1977-06-17 Cable electrique haute tension a ame a resistances en fibre de verre
DE19772731356 DE2731356A1 (de) 1976-07-14 1977-07-12 Hochspannungskabel
FR7721819A FR2358734A1 (fr) 1976-07-14 1977-07-13 Cable electrique allonge de connexion d'un pistolet de pulverisation electrostatique
GB29488/77A GB1583056A (en) 1976-07-14 1977-07-13 Resistor core cable
JP52083630A JPS6047683B2 (ja) 1976-07-14 1977-07-14 高圧ケ−ブル
IT50272/77A IT1079309B (it) 1976-07-14 1977-07-14 Cavo ad anima resistiva

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/705,363 US4103276A (en) 1976-07-14 1976-07-14 Resistor core cable

Publications (1)

Publication Number Publication Date
US4103276A true US4103276A (en) 1978-07-25

Family

ID=24833136

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/705,363 Expired - Lifetime US4103276A (en) 1976-07-14 1976-07-14 Resistor core cable

Country Status (7)

Country Link
US (1) US4103276A (fr)
JP (1) JPS6047683B2 (fr)
CA (1) CA1088167A (fr)
DE (1) DE2731356A1 (fr)
FR (1) FR2358734A1 (fr)
GB (1) GB1583056A (fr)
IT (1) IT1079309B (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4576827A (en) * 1984-04-23 1986-03-18 Nordson Corporation Electrostatic spray coating system
US4739935A (en) * 1986-03-12 1988-04-26 Nordson Corporation Flexible voltage cable for electrostatic spray gun
US4784331A (en) * 1987-05-27 1988-11-15 Nordson Corporation Electrostatic spray gun device and cable assembly
US6144018A (en) * 1993-02-08 2000-11-07 Heizer; Glenwood Franklin Heating cable
US6559376B2 (en) * 1996-09-30 2003-05-06 Nology Engineering, Inc. Combustion initiation device and method for tuning a combustion initiation device
US20090260852A1 (en) * 2008-02-29 2009-10-22 Fort Wayne Metals Research Products Corporation Alternating core composite wire
CN112820460A (zh) * 2020-12-29 2021-05-18 河北亿正线缆有限公司 一种可防缠绕式的电线电缆

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62105085U (fr) * 1985-12-24 1987-07-04
JPS62146689U (fr) * 1986-03-11 1987-09-16
JPH10208505A (ja) * 1997-01-24 1998-08-07 Koito Mfg Co Ltd 車輌用前照灯

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045199A (en) * 1960-12-12 1962-07-17 Stackpole Carbon Co Engine ignition system cable
US3167255A (en) * 1961-05-08 1965-01-26 Sames Mach Electrostat Electrostatic sprayer system having a separate high resistivity conductor
US3348186A (en) * 1964-11-16 1967-10-17 Nordson Corp High resistance cable
US3657520A (en) * 1970-08-20 1972-04-18 Michel A Ragault Heating cable with cold outlets
US3792409A (en) * 1973-04-02 1974-02-12 Ransburg Corp Electrostatic hand gun cable

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2119236C3 (de) * 1971-04-21 1975-06-19 Aeg Isolier- Und Kunststoff Gmbh, 3500 Kassel Schichtpreßstoff als Potentiometermaterial

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045199A (en) * 1960-12-12 1962-07-17 Stackpole Carbon Co Engine ignition system cable
US3167255A (en) * 1961-05-08 1965-01-26 Sames Mach Electrostat Electrostatic sprayer system having a separate high resistivity conductor
US3348186A (en) * 1964-11-16 1967-10-17 Nordson Corp High resistance cable
US3657520A (en) * 1970-08-20 1972-04-18 Michel A Ragault Heating cable with cold outlets
US3792409A (en) * 1973-04-02 1974-02-12 Ransburg Corp Electrostatic hand gun cable

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4576827A (en) * 1984-04-23 1986-03-18 Nordson Corporation Electrostatic spray coating system
US4739935A (en) * 1986-03-12 1988-04-26 Nordson Corporation Flexible voltage cable for electrostatic spray gun
US4784331A (en) * 1987-05-27 1988-11-15 Nordson Corporation Electrostatic spray gun device and cable assembly
US6144018A (en) * 1993-02-08 2000-11-07 Heizer; Glenwood Franklin Heating cable
US6559376B2 (en) * 1996-09-30 2003-05-06 Nology Engineering, Inc. Combustion initiation device and method for tuning a combustion initiation device
US20090260852A1 (en) * 2008-02-29 2009-10-22 Fort Wayne Metals Research Products Corporation Alternating core composite wire
US7989703B2 (en) 2008-02-29 2011-08-02 Fort Wayne Metals Research Products Corporation Alternating core composite wire
CN112820460A (zh) * 2020-12-29 2021-05-18 河北亿正线缆有限公司 一种可防缠绕式的电线电缆

Also Published As

Publication number Publication date
FR2358734B1 (fr) 1984-03-09
JPS5310075A (en) 1978-01-30
JPS6047683B2 (ja) 1985-10-23
DE2731356A1 (de) 1978-01-19
CA1088167A (fr) 1980-10-21
FR2358734A1 (fr) 1978-02-10
IT1079309B (it) 1985-05-08
GB1583056A (en) 1981-01-21
DE2731356C2 (fr) 1989-04-06

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